For the photoconductive material to constitute a light receiving layer in a light receiving member for use in electrophotography, it is required to be highly sensitive, to have a high SN ratio [photocurrent (Ip)/dark current (Id)], to have absorption spectrum characteristics suited for the spectrum characteristics of an electromagnetic wave to be irradiated, to be quickly responsive and to have a desired dark resistance. It is also required to be not harmful to living things as well as man upon use.
Especially, it is where it is the light receiving member is to be applied in an electrophotographic machine for use in office then, causing no pollution is indeed important.
From this standpoint, public attention has been focused on light receiving members comprising amorphous materials containing silicon atoms (hereinafter referred to as "a-Si"), for example, as disclosed in Offenlegungsschriftes Nos. 2746967 and 2855718 which disclose use of the light receiving member as an image-forming member in electrophotography.
For the conventional light receiving members comprising a-Si materials, there have been made improvements in their optical, electric and photoconductive characteristics such as dark resistance, photosensitivity, and photoresponsiveness, use-environmental characteristics, economic stability and durability.
However, there are still further improvements to be made in their characteristics in the synthesis situation in order to make such light receiving members practically usable.
For example, when such a such conventional light receiving member is employed in the light receiving member for use in electrophotography with the aim to raise the photosensitivity and dark resistance, there is often observed a residual voltage on the conventional light receiving member upon. When it is repeatedly used for a long period of time, fatigues due to the repeated use will accumulate and to cause the so-called ghost phenomena producing residual images.
Further, in the preparation of the light receiving layer of the conventional light receiving member for use in electrophotography using an a-Si material, hydrogen atoms, halogen atoms such as fluorine atoms or chlorine atoms, elements for controlling the electrical conduction type such as boron atoms or phosphorus atoms, or other kinds of atoms for improving the characteristics are selectively incorporated in the light receiving layer.
However, the resulting light receiving layer sometimes becomes accompanied with defects on the electrical characteristics, photoconductive characteristics and/or breakdown voltage according to the way of the incorporation of said constituents to be employed.
That is, in the case of using the light receiving member having such light receiving layer, the life of a photocarrier generated in the layer with the irradiation of light is not sufficient, the inhibition of a charge injection from the side of the substrate in a dark layer region is not sufficiently carried out, and image defects likely due to a local breakdown phenomenon which is so-called "white oval marks on half-tone copies" or other image defects likely due to abrasion upon using a blade for the cleaning which is so-called "white line" are apt to appear on the transferred images on a paper sheet.
Further, in the case where the above light receiving member is used in a very moist atmosphere, or in the case where after being placed in that atmosphere it is used, the so-called "image flow" sometimes appears on the transferred images on a paper sheet.
In consequence, it is necessary not only to make a further improvement in an a-Si material itself but also to form such a light receiving member so as not to invite any of the foregoing problems.